'use strict';

const aws = require('aws-sdk');

const project = require('../config/project.config.js');

const options = {

region: 'eu-west-1',

};

function listObjects(s3, params) {

return new Promise((resolve, reject) => {

s3.listObjects(params, (err, data) => {

if (err) return reject(err);

return resolve(data);

});

});

}

function trimPrefix(prefix) {

const pattern = /examples\/(\w+)\//;

return prefix.match(pattern)[1];

}

function trimItem(key) {

const pattern = /examples\/\w+\/(.*)/;

return key.match(pattern)[1];

}

function makeBody(data) {

const result = {};

data.forEach((set) => {

result[trimPrefix(set.Prefix)] = set.Contents.map((item) => trimItem(item.Key));

});

return {

examples: result,

};

}

module.exports.handler = (event, context, callback) => {

const s3 = new aws.S3(options);

const params = {

Bucket: project.bucket_name,

Delimiter: '/',

Prefix: 'examples/',

};

s3.listObjects(params, (err, data) => {

if (err) return callback(err);

const prefixes = data.CommonPrefixes.map((item) => item.Prefix);

Promise.all(prefixes.map((prefix) =>

listObjects(s3, {

Bucket: project.bucket_name,

Delimiter: '/',

Prefix: prefix,

})

)).then((data) => {

const content = makeBody(data);

const response = {

statusCode: 200,

headers: {

'Access-Control-Allow-Origin': '*',

},

body: JSON.stringify(content),

};

return callback(null, response);

}).catch((err) => {

return callback(err);

});

});

};